Holocene evolution of summer winds and marine productivity in the tropical Indian Ocean in response to insolation forcing: data-model comparison

The relative abundance of <i>Globigerinoides bulloides</i> was used to infer Holocene paleo-productivity changes on the Oman margin and at the southern tip of India. Today, the primary productivity at both sites reaches its maximum during the summer season, when monsoon winds result in local Eckman pumping, which brings more nutrients to the surface. On a millennium time-scale, however, the % <i>G. bulloides</i> records indicate an opposite evolution of paleo-productivity at these sites through the Holocene. The Oman Margin productivity was maximal at ~9 ka (boreal summer insolation maximum) and has decreased since then, suggesting a direct response to insolation forcing. On the contrary, the productivity at the southern tip of India was minimum at ~9 ka, and strengthened towards the present. <br><br> Paleo-reconstructions of wind patterns, marine productivity and foraminifera assemblages were obtained using the IPSL-CM4 climate model coupled to the PISCES marine biogeochemical model and the FORAMCLIM ecophysiological model. These reconstructions are fully coherent with the marine core data. They confirm that the evolution of particulate export production and foraminifera assemblages at our two sites were directly linked with the strength of the upwelling. Model simulations at 9 ka and 6 ka BP show that the relative evolution between the two sites since the early Holocene can be explained by the weakening but also the southward shift of monsoon winds over the Arabian Sea during boreal summer

Modeling of axonal endoplasmic reticulum network by spastic paraplegia proteins

Axons contain a smooth tubular endoplasmic reticulum (ER) network that is thought to be continuous with ER throughout the neuron; the mechanisms that form this axonal network are unknown. Mutations affecting reticulon or REEP proteins, with intramembrane hairpin domains that model ER membranes, cause an axon degenerative disease, hereditary spastic paraplegia (HSP). We show that Drosophila axons have a dynamic axonal ER network, which these proteins help to model. Loss of HSP hairpin proteins causes ER sheet expansion, partial loss of ER from distal motor axons, and occasional discontinuities in axonal ER. Ultrastructural analysis reveals an extensive ER network in axons, which shows larger and fewer tubules in larvae that lack reticulon and REEP proteins, consistent with loss of membrane curvature. Therefore HSP hairpin-containing proteins are required for shaping and continuity of axonal ER, thus suggesting roles for ER modeling in axon maintenance and function.RCUK | Biotechnology and Biological Sciences Research Council (BBSRC): Lu Zhao, Cahir J O'Kane, BB/L021706/1; Wellcome: Martin Stofanko, Cahir J O'Kane, 08136; European Commission (EC): Lu Zhao, Niamh C O'Sullivan, Sophie Zaessinger, Olivier Blard, MCSA fellowships 220851,220874,236777,660516; Yousef Jameel Foundation: Belgin Yalçın; Singapore A*STAR Scholarship: Zi Han Kang, BM/RES/07/005; Cambridge Commonwealth, European and International Trust (Cambridge Commonwealth, European & International Trust): Belgin Yalçın, Anood Sohail; Pakistan Higher Education Council Scholarship: Anood Sohail; Motor Neurone Disease Association (MNDA): Alex L Patto, Studentship 861-792 The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication

Implicating Calpain in Tau-Mediated Toxicity In Vivo

Alzheimer's disease and other related neurodegenerative disorders known as tauopathies are characterized by the accumulation of abnormally phosphorylated and aggregated forms of the microtubule-associated protein tau. Several laboratories have identified a 17 kD proteolytic fragment of tau in degenerating neurons and in numerous cell culture models that is generated by calpain cleavage and speculated to contribute to tau toxicity. In the current study, we employed a Drosophila tauopathy model to investigate the importance of calpain-mediated tau proteolysis in contributing to tau neurotoxicity in an animal model of human neurodegenerative disease. We found that mutations that disrupted endogenous calpainA or calpainB activity in transgenic flies suppressed tau toxicity. Expression of a calpain-resistant form of tau in Drosophila revealed that mutating the putative calpain cleavage sites that produce the 17 kD fragment was sufficient to abrogate tau toxicity in vivo. Furthermore, we found significant toxicity in the fly retina associated with expression of only the 17 kD tau fragment. Collectively, our data implicate calpain-mediated proteolysis of tau as an important pathway mediating tau neurotoxicity in vivo

Uncoupling neuronal death and dysfunction in Drosophila models of neurodegenerative disease

Common neurodegenerative proteinopathies, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), are characterized by the misfolding and aggregation of toxic protein species, including the amyloid beta (Aß) peptide, microtubule-associated protein Tau (Tau), and alpha-synuclein (αSyn) protein. These factors also show toxicity in Drosophila; however, potential limitations of prior studies include poor discrimination between effects on the adult versus developing nervous system and neuronal versus glial cell types. In addition, variable expression paradigms and outcomes hinder systematic comparison of toxicity profiles. Using standardized conditions and medium-throughput assays, we express human Tau, Aß or αSyn selectively in neurons of the adult Drosophila retina and monitor age-dependent changes in both structure and function, based on tissue histology and recordings of the electroretinogram (ERG), respectively. We find that each protein causes a unique profile of neurodegenerative pathology, demonstrating distinct and separable impacts on neuronal death and dysfunction. Strikingly, expression of Tau leads to progressive loss of ERG responses whereas retinal architecture and neuronal numbers are largely preserved. By contrast, Aß induces modest, age-dependent neuronal loss without degrading the retinal ERG. αSyn expression, using a codon-optimized transgene, is characterized by marked retinal vacuolar change, progressive photoreceptor cell death, and delayed-onset but modest ERG changes. Lastly, to address potential mechanisms, we perform transmission electron microscopy (TEM) to reveal potential degenerative changes at the ultrastructural level. Surprisingly, Tau and αSyn each cause prominent but distinct synaptotoxic profiles, including disorganization or enlargement of photoreceptor terminals, respectively. Our findings highlight variable and dynamic properties of neurodegeneration triggered by these disease-relevant proteins in vivo, and suggest that Drosophila may be useful for revealing determinants of neuronal dysfunction that precede cell loss, including synaptic changes, in the adult nervous system

Les Fourmis de l'île de la Réunion (Hymenoptera, Formicidae)

Ants of Réunion Island (Hymenoptera, Formicidae). In this study, 27 ant species are reported with 15 new for the island. Half of the ant fauna is composed of "tramp species" and only two endemic species of the Mascarene Islands have been found. Distribution, ecology and biogeography are discussed.Cette étude sur la myrmécofaune de l'île de la Réunion a permis d'inventorier 27 espèces dont 15 nouvelles pour l'île. Si l'on ne compte que deux espèces endémiques des Mascareignes, plus de la moitié des espèces présentes sont des fourmis "vagabondes". Leur distribution, écologie et origine biogéographique sont discutées.Blard Fabrice, Dorow Wolfgang-H.-O., Delabie Jacques H.C. Les Fourmis de l'île de la Réunion (Hymenoptera, Formicidae). In: Bulletin de la Société entomologique de France, volume 108 (2), juin 2003. pp. 127-137

Les Fourmis de l'île de la Réunion (Hymenoptera, Formicidae)

Ants of Réunion Island (Hymenoptera, Formicidae). In this study, 27 ant species are reported with 15 new for the island. Half of the ant fauna is composed of "tramp species" and only two endemic species of the Mascarene Islands have been found. Distribution, ecology and biogeography are discussed.Cette étude sur la myrmécofaune de l'île de la Réunion a permis d'inventorier 27 espèces dont 15 nouvelles pour l'île. Si l'on ne compte que deux espèces endémiques des Mascareignes, plus de la moitié des espèces présentes sont des fourmis "vagabondes". Leur distribution, écologie et origine biogéographique sont discutées.Blard Fabrice, Dorow Wolfgang-H.-O., Delabie Jacques H.C. Les Fourmis de l'île de la Réunion (Hymenoptera, Formicidae). In: Bulletin de la Société entomologique de France, volume 108 (2), juin 2003. pp. 127-137

Research data supporting "Modeling of axonal endoplasmic reticulum network by spastic paraplegia proteins"

The supporting data include sequence analyses, microscopy, electron microscopy, quantitative analyses and reconstructions of images, and statistical analyses, for each figure presented in the paper.Listed in 10.7554/eLife.2388

A direct-sampling multi-channel receiver for DOCSIS 3.0 in 65nm CMOS

This paper presents a fully integrated direct sampling receiver for DOCSIS 3.0, consisting of a time-interleaved ADC, a digital multi-channel selection filter, and a PLL. The receiver can simultaneously receive 4 streams from arbitrary RF frequencies between 48 and 1002MHz and output these in a 13.5MS/s digital IQ format or at a low-IF through integrated DACs. It consumes 980mW from a split 1.2/1.3/1.6V supply when receiving 4 channels and occupies 16.8mm2 in 65nm CMOS